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A method for measuring the forces acting on a tree trunk using strain gauges

The wind force acted on a tree constantly changes in magnitude, direction, and distribution. We developed a method to measure simultaneously the amount of force (F), centroid of the distributed force (C), and direction of force (D) on a tree trunk using four strain gauges. F and C were estimated fro...

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Autores principales: Miyashita, Ayana, Suzuki, Satoru
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7810299/
https://www.ncbi.nlm.nih.gov/pubmed/33449960
http://dx.doi.org/10.1371/journal.pone.0245631
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author Miyashita, Ayana
Suzuki, Satoru
author_facet Miyashita, Ayana
Suzuki, Satoru
author_sort Miyashita, Ayana
collection PubMed
description The wind force acted on a tree constantly changes in magnitude, direction, and distribution. We developed a method to measure simultaneously the amount of force (F), centroid of the distributed force (C), and direction of force (D) on a tree trunk using four strain gauges. F and C were estimated from the difference in the bending moments at two different positions along the long axis of the stem. D was estimated using the difference in the sensor outputs at two different radial positions at the same height. In principle, the two strain gauges should be oriented precisely 90° apart; however, this is unrealistic on an actual tree trunk. To calculate D, we developed a new method to detect the radial position and modulus of elasticity of each strain gauge after attaching it. We conducted three types of experiment. First, we loaded a wood pole with weights arranged in 11 patterns to test the accuracies of F and C for a distributed load. Next, we applied tensile forces to the wood pole and an evergreen conifer sapling from eight directions to test the accuracy of D, F, and C. On average, estimation errors were < 2% for both the distributed load and circumferential tensile load. Our method can estimate F, C, and D precisely, even if the wood is uneven and the strain gauges are not aligned. This is a great advantage for field wind force measurements.
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spelling pubmed-78102992021-01-27 A method for measuring the forces acting on a tree trunk using strain gauges Miyashita, Ayana Suzuki, Satoru PLoS One Research Article The wind force acted on a tree constantly changes in magnitude, direction, and distribution. We developed a method to measure simultaneously the amount of force (F), centroid of the distributed force (C), and direction of force (D) on a tree trunk using four strain gauges. F and C were estimated from the difference in the bending moments at two different positions along the long axis of the stem. D was estimated using the difference in the sensor outputs at two different radial positions at the same height. In principle, the two strain gauges should be oriented precisely 90° apart; however, this is unrealistic on an actual tree trunk. To calculate D, we developed a new method to detect the radial position and modulus of elasticity of each strain gauge after attaching it. We conducted three types of experiment. First, we loaded a wood pole with weights arranged in 11 patterns to test the accuracies of F and C for a distributed load. Next, we applied tensile forces to the wood pole and an evergreen conifer sapling from eight directions to test the accuracy of D, F, and C. On average, estimation errors were < 2% for both the distributed load and circumferential tensile load. Our method can estimate F, C, and D precisely, even if the wood is uneven and the strain gauges are not aligned. This is a great advantage for field wind force measurements. Public Library of Science 2021-01-15 /pmc/articles/PMC7810299/ /pubmed/33449960 http://dx.doi.org/10.1371/journal.pone.0245631 Text en © 2021 Miyashita, Suzuki http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Miyashita, Ayana
Suzuki, Satoru
A method for measuring the forces acting on a tree trunk using strain gauges
title A method for measuring the forces acting on a tree trunk using strain gauges
title_full A method for measuring the forces acting on a tree trunk using strain gauges
title_fullStr A method for measuring the forces acting on a tree trunk using strain gauges
title_full_unstemmed A method for measuring the forces acting on a tree trunk using strain gauges
title_short A method for measuring the forces acting on a tree trunk using strain gauges
title_sort method for measuring the forces acting on a tree trunk using strain gauges
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7810299/
https://www.ncbi.nlm.nih.gov/pubmed/33449960
http://dx.doi.org/10.1371/journal.pone.0245631
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